Mini-Brains: The Cutting Edge of Neurological Disorders Treatment Research

Richard Jacobs: Hello, this is Richard Jacobs with the Finding Genius podcast, the health, medicine, and bio-science edition. My job here is to find the top people in their fields. This could be one in 500 people, one in a thousand, but they’re usually really good at what they do. I want to ask him questions they haven’t been asked before, hopefully, and get some great information for you, the listener, so that you learn something and then maybe it improves your health and your life, your family’s life. That’s the goal here. So, today I have Paula Barreras. She is a post-doc at Johns Hopkins and a working in neurology on brain organoids. Are there approximations of the brain? Yeah, they may be really good approximations or really narrow approximations, but scientists can test various drugs on them and protocols to see how a real brain might work. And then you don’t have to use an animal, hopefully. So that’s my understanding of organoids. But Paula, thanks for coming. How are you doing?

Paula Barreras: I’m doing well. Thanks, Richard for inviting me

Richard Jacobs: And I hope my, my organoid brain was able to speak about brain organoids in the right way. Is that correct what I said?

Paula Barreras: Yeah, so this is a very interesting new technology. It’s basically a small sphere of the human cells that we managed to convert into neurons and glial cells, which are the supporting cells for the neurons in co-culture in vitro, which is notoriously hard to achieve. As you said, most of the studies are based on animal models and animals are not humans, not genetically or physiologically. And that creates a big issue of studies failing when translating to human studies from animal studies. And we believe that the use of technologies that are human-based can help reach that barrier, in drug screening and other studies.

Richard Jacobs: So I know we can’t make a whole brain or a whole organ, but, so what functions of the brain are you trying to approximate? What kind of cells and what kind of structure?

Paula Barreras: Right. So we’re trying to first achieve the presence of mature neurons and glial cells which is different from just a ball of STEM cells. And we are trying to approximate the interactions between these cells as close as possible to normal human adult brains. So these mini-brains or brain organoids have actually a few features of mature human brains, including synopsis, meaning neurons talking to each other and interacting in a functional way. There’s evidence of early myelination that’s oligodendrocytes, which are the cells that make the wrapping around axons. We’re seeing those mature cells present in our culture and they’re starting to wrap around the axons, which is something novel of these models. And there’s also a spontaneous electrical activity.

Richard Jacobs: That’s amazing. What kind of medical conditions do you hope to approximate or test with the organoids?

Paula Barreras: Well, the great thing about his model is that the way it’s made is starting with skin cells of a donor. And you could imagine that you can use any donor, either a healthy volunteer or a patient with a particular disease. So in theory, you could use this model to do personalized testing for many different brain conditions. We’ve used healthy donors to produce healthy brain organoids and expose them to different viruses, for example, to test for the susceptibility of different types of brain cells to infections and understand more about these types of infections we used it, for example, with the Zika virus when the outbreak happened in 2016. But the other thing that we can use them for is to study particular brain disorders by using or bruising organoids from patients in particular since this model has Mylyn, which is very hard to have in culture. You could think about using it for myelinating disorders such as multiple sclerosis.

Richard Jacobs: So, it’s weird using skin cells, I guess you have to walk them back development wise to induce pro prudency in them and then guide them on the pathway down. And we can get brain cells, right?

Paula Barreras: Yeah, that’s correct. So we start with adult human skin cells. Those are called fibroblasts. And then we induce them back to be STEM cells. And from that stage, we induce them to become neural progenitor cells, which later develop into neurons, astrocytes and little undersides, which are the main cell types in the human brain.

Richard Jacobs: That must have taken a lot of time and effort to figure out how to first induce pro prudency and then, you know, walked them down the pathways, they need to go to create all those kinds of cells. There is a lot of people working on this.

Paula Barreras: It did. So we were not the first group that manages to produce progenitor cells. Fortunately, there’s a lot of very smart people working on how to use these technologies. But I do think we’re one of the first, if not the first to manage, to have co-culture of these adult phenotype brain cells with functional features. But did take a lot of trial and error and long nights at the lab.

Richard Jacobs: So where are you at right now with the research? Are you still trying to attune the organoids so that they will approximate the functions you want or they’re good enough and now you want to start testing the effects of different diseases on, for instance, myelination or other things?

Paula Barreras: Well, we would think they’re good enough now. The first main part of the research was trying to not only produce them but make them standardized such that every time you would produce them, they would be similar to each other. And that phase is done within. We are able to make that reproducible model and make them similar to each other each time. Then the next phase was to characterize which cell types we have, how mature are they over time, what’s the optimal time to culture them. And we think that’s optimized now and right now we’re starting to use them for testing different molecules or different experiments. One of them is, for example, the JC virus, which is a virus that can cause severe neurological disease in the immunocompromised and people with HIV or taking immunosuppressant drugs. So we have started some experiments to expose the brain organoids to this virus and have gotten some interesting.

Richard Jacobs: What is the blood-brain barrier composed of and using that might be necessary to really approximate the function of this organoid. What if you were able to culture a barrier and then you let the virus loose of the outside of the barrier or whatever it was and it had to migrate through it and then maybe it would approximate what happens in the brain better? I don’t know.

Paula Barreras: Yeah, that’s a great question. And it’s probably one of the main limitations of this type of model. The model doesn’t have blood vessels and therefore we cannot have a brain blood barrier in that sense. So the blood-brain barrier, like you sort of said, is that the barrier between the blood, the blood vessels, and the brain and there’s a lot of cell types and interactions between the blood vessel wall and the astrocytes, which is the main cell that helps form that barrier. And we don’t really have that in this model. So by putting the virus directly, we’re assuming or recreating this scenario where the virus has already gone through the brain-blood barrier. There have been some experiments that we’ve tried to try to approximate what a blood-brain barrier would look like by using endothelial membranes and putting the brain organics on one side and the toxins on the other side. So there are ways to get around it, but our model doesn’t have a blood-brain barrier as such.

Richard Jacobs: Well, what about in the different parts of the brain? It will be really hard I guess to even create mini versions of the medulla and the cortex, everything. I don’t know, I guess is the motto sophisticated enough where you’ll learn plenty from it at this stage and is there a plan to really make truly a mini-brain with different areas?

Paula Barreras: Yeah. Well like you said, that’s very hard to make. And I think that the models that have been attempted by your groups and with limited success and the reason that’s the case, it’s because as the larger an in vitro model becomes just the size because there are no blood vessels. There are no nutrients that can reach the center of the sphere or the center of the model. And then it starts causing cell death in the middle. And then as the more complex a model is the more variability there is between each individual organoid. So our model is simpler in that sense. It’s an aggregate of the three main cell types and its small, its 300 microns. But the good thing is that is always the same. So we cannot use it to say study specifically what would happen in an inner region of the brain, but we can use it to study specifically what would happen in a particular cell type or with the interaction between, let’s say astrocytes and neurons in a particular viral infection or toxin exposure. So it serves a little bit of a different function. But we think that’s actually better if you want to create reproducible scientific parameters that you can measure.

Richard Jacobs: Interesting. Has anyone in the organoid field been able to grow blood vessels so they can make denser more complicated structures or is that just a hold back on anyone working in organoids?

Paula Barreras: So there are some groups producing blood vessels and that’s like its own project. I don’t think to my knowledge that there’s a brain organoid with blood vessels incorporated in it. But that’s certainly a next step that I think is worth exploring. Because it’s a big limitation to grow them in like in larger sizes.

Richard Jacobs: Okay. One thing that came to mind I know in a lot of cell types put out extracellular vesicles, lots of them, but in the brain, I’m sure a lot of the cells communicated through neurologically. I wonder if they have much of a need for EV’s and if they put them out and is that a part of your model at all? Have you seen any of them come out in the organoid and of the cells?

Paula Barreras: So if I’ve seen vesicles come out of their lineage?

Richard Jacobs: Yeah. If they are putting out any extracellular vesicles, any organoid cells?

Paula Barreras: Yeah. So we saw a few things. We saw that they’re synoptic structures and when there’s a synoptic communication between neurons, they’re bicycles of neurotransmitters that are produced. And we were able to measure markers of such neurotransmission in the model. So we know that there is at least, you know, that type of vesicles being produced. When we did electro microscopy, we saw evidence of small vesicles inside the cells being produced. So there is some of that, we haven’t really measured that as an outcome, like as an endpoint in the extracellular fluid. But for example, when we were testing for infection, we were able to measure new viral production by the organoid which is presumably through an excursion of vesicles containing the virus.

Richard Jacobs: So any interesting behaviors you’ve seen from the organoids you make or you’re testing as you said, certain viruses on them, an experiment or results that are really unusual and cool?

Paula Barreras: Yeah. I think one of the coolest things about this model is the presence of myelin, and to understand how important that is you have to understand that myelin is produced by oligodendrocytes and they are very hard to culture. And because of that, most studies in diseases like multiple sclerosis are based in mice and a lot of the trials fail and whatnot. And that’s probably because the biology is not the same. This model has mature looking oligodendrocytes, which is rare. And it’s actually a surprising finding that we were not expecting to see. And then when we saw these oligodendrocyte cells are actually wrapping the axons we were very happy and very surprised about that cause that’s usually not what you achieve in culture. I think we’re seeing that because the presence of fosters I’d seen in the same culture enhances like it approximates more than normal biology of the human brain. And broadly they’re signaling that you wouldn’t have in a, let’s say, a culture juice with a legal interest like precursors. So this presence of myelin was very exciting for us and we can quantify it in a standardized way. And then we saw that the older the organoid gets the more myelin its produce. I think that’s a big deal for us because now we can start thinking about testing agents for remediation for example, which we haven’t done yet, but it’s sort of like the future of the multiple sclerosis field, I think. For viruses, we were able to infect these oligodendrocyte cells with the JC virus. And the JC virus is a very tricky virus because it can only infect human cells. And because of that, there’s no animal model to date available to study that disorder and therefore no effective treatments because there’s really no model to test the treatment. And so now that we saw that we’re actually able to achieve infection in that model, that’s very exciting and that has us thinking about testing different chemicals thinking about new treatments for that disorder.

Richard Jacobs: Okay. I’m not sure what to ask you about this. Well, in terms of protocols, I know those mouse models that are like the gold standard, in general when do you think organoids will be part of the clinical trial process? When will they be used more than animal models, let’s say?

Paula Barreras: Well, that’s the dream in a way. So animal models have a lot of limitations, like I’ve said already, but also some ethical issues with animal treatment and cruelty. And if we are able to prove that you can get not only good enough data but even better data based on having human cells in a model than animal data, then I think that will sort of turn the corner and say, okay, let’s use more relevant human models for clinical trials. I don’t think we’re quite there yet because this technology is relatively new and a lot of the drug developing companies are very familiar with animal models and not so much with this type of technology. But I think there’s more and more interest from drug developing companies in these types of technology. I imagine in the next 10 years this will be used more and more and maybe at that stage we’ll change gears and start using these types of technology instead of animal models.

Richard Jacobs: Yeah. Cause you’re in the field. I just wonder when an update was, is it still way far in the future or does it seem to be getting close?

Paula Barreras: It’s getting closer and closer. Depending on the use I see one thing is closer than others. For example, using this model to screen, to evaluate the toxicity of different substances. I think that’s closer in the future than using it, for example, to study diseases like multiple sclerosis using it to test compounds as treatment for viral infections. I think that’s very plausible. And nearing the future is relatively easy to do. We can produce 800 of these organoids at a time so that we can produce many of them and treat them in different, at the same time put them in different Wells and expose them to many different substances. And that makes it way cheaper than doing that with animal models that take longer to be produced and they’re more expensive. So I think the companies, the drug testing companies will be interested in this type of model just because you can massively produce it, it is cheaper. And his personal agreement, you know, more accurate depending on what you want to measure.

Richard Jacobs: So when you do your experiments, do you do like a hundred organoids at a time where they really cheap to make and easy or they still difficult?

Paula Barreras: I think they’re cheap and easy for me. We make let’s say 800 and when we test, I would say I use something like 80 in an experiment with the standard would be, let’s say your test includes different experiment conditions and you put 30 or 20 in each well and expose them to that. And you don’t need that many. With just one organoid, you have a lot of information, but for reproducibility of your experiments, you want to test up to this, five of them per condition. So it’s really easy to have enough material to reproduce experiments and there’s multiple conditions and that’s not true for let’s say mice. Because they’re harder to work with.

Richard Jacobs: So what does that allow you to do in your experimentation? You know, it’s like having a whole bunch of animal models in a sense. I mean, you’re able to, I guess, test many at one time,

Paula Barreras: Right. You can test many at one time. And I think importantly, many different conditions at one time. So like you can put out a dish with 90 Wells and put five of these organisms in it as well. And 90 different conditions in one experiment, which is really hard to do with larger, bulkier models like a mouse.

Richard Jacobs: Okay. So what other experiments are you doing? What are you trying to figure out right now with organoids?

Paula Barreras: Well, right now we’re focusing a lot on the JC virus infection. Another thing we were trying to do is working with HIV cause there’s a condition that, so people that have longstanding HIV, we’re starting to see a cognitive decline, basically dementia that is believed to be caused directly by the virus. And some studies have suggested that that’s the virus infecting some of the glial cells. And the mechanisms by which that happens are not well understood. So we are interested in looking into that, exposing these organoids to HIV and sort of studying the susceptibility of these different cells to the virus and see if there’s anything we can do to stop the spread if cause this happens, this cognitive decline happens is by people being an adequate therapy for the HIV. So the mechanism is spelled to be different and is not understood. So that’s our use of this model. You can use it to not only test compounds or test infections, but to try to understand the mechanism of disease because you can measure gene expression. So two cell interactions so we’re looking into that for the HIV infection as well.

Richard Jacobs: Hmm. Okay. Well, very good. What’s the best way for people to find out more and maybe if they could see some of the organoids, if you have any pictures, but how can they find out more from here?

Paula Barreras: Yeah. Well, I think we have a couple of papers on the model that have pictures. I think this model was done in collaboration with the School of public health group Johns Hopkins and that’s David Pammie’s and Helena Hochberg and they have in their website a video like a YouTube link to, a little bit of how the process is meant to that. That would be a good way for people to find out that hopefully, we’ll be putting out more information and more papers that people can access.

Richard Jacobs: All right. Well, very good. Well, Paula, thank you for coming. The organoid field is like I said, it’s amazing. It’s really cool and the brain is probably the most interesting part of it, so that’s great. What’s the best way for people to, again, find out more like a URL of a website where your research is? You know, how can they do it?

Paula Barreras: Like if you go to the website of the School of public health lab they have, they have a good video about it. And I think if you type a mini-brain Hopkins then you get like very fast to the website that we have there with some basic information. There’s a link to a video that people can access.

Richard Jacobs: Well, if any person comes up when you put in mini-brain, you know, that would be an insult to them. Well, thank you for coming. It’s been a very quick call. I appreciate it.

Paula Barreras: Thank you for inviting me.